Electric furnace



' Patented Aug. 2, 1927.

UNITED `STATES PATENT OFFICE.

JAMES KELLEHER, OF CHIPPAWA, ONTARIO, CANADA, ASSIGNOR T0 HARPER ELEC- TRIG FURNACE CORPORATION, A CORI'ORATION' OF NEW YORK.

ELECTRIC FURNACE.

Application ltiled July 17, 1925. Serial No. 44,183.

This invention relates to electric furnaces of the type which employ carbonaceous resistors and particularly to an improved construction of such furnaces whereby deterioration ot' the resistors employed is minimized. lt has been found that it the resistor in such furnaces is surrounded by retractories such as silica brick, ire-clay brick or other refractory containing silicon in a silicate or other form, these silicates at high temperatures will decompose and .silicon vapors will attack the carbonareous resistor,

forming thereon silicon carbide, and this' causes deterioration of the resistor. lThis reaction may take place at comparati\-'ely low tcniperatures, the temperature at which it takes place being largely dependent upon the refractory surrounding the resistor and upon atmospheric conditions existing in the neighborhood of the refraetories.

The major object of the present invention is to prevent such deterioration by providingu protective inner lining for the refractorics forming the walls of the resistor chamber. Other objects will appear from the following description, taken 1n connection with the accompanying drawing, wherein Fig. 1 represents a` horizontal section through the furnace resistor chamber, and

Fig. 2 a fragmentary section through the roof of the furnace taken on the line A2--2 of Fig. 1.

In the drawings, 1 represents the outer walls of the furnace, 2 a resistor chamber containing a resistor formed of some carbonaceous material. 4 is an inner lining for the 'resistor chamber composed of Acheson graphite or some other carbonaceous materialin the form of plates, and 5 is the roof of the resistor chamber composed of the same material as the plates 4. If desired preferably a powder which can be packed around the plates 4. This material is stable up to a tenmeratureabove 2000O C. and the silicon contained in this material will not be liberated until an extremely high tem-.

perature has been reached By varying the thickness of the packing 6 between the plates 4 and the walls l, the danger of silicon vapors entering into the resistor chamber 2 from the silicious refractories in the walls l is practically eliminated.

I claim:

1. An electric furnace comprising end and side walls of refractory silicon material enclosino` a chamber, a carbonaceous resistor exten ing through said chamber fromend to end, an Ainner lining of carbonaceous material surrounding said resistor and forming a. chamber therefor, and a. packing between the inner lining-and the outer wa l of sucient thickness to avoid entrance of silicon vapor from said walls into said resistor chamber. i

2. An electric furnace formed with a.l

chamber having wallsformed of refractories containing silicon and an inner lining for said walls comprising plates of carbonaceous material, and a packing ofamorphous silicon Carbine between said plates and refractories,

and a Carbonaceous resistorin said chamber.

' JAMES KELLEHER.' 

